Power bank



FIG. 1 is a top front perspective view of a power bank;

FIG. 2 is a front elevation view thereof:

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a right side elevation view thereof;

FIG. 5 is a left side elevation view thereof;

FIG. 6 is a top elevation view thereof;

FIG. 7 is a bottom elevation view thereof; and,

FIG. 8 is an exploded perspective view thereof.

The broken lines in the drawings are for the purpose of illustrating portions of the power bank that form no part of the claimed design. 

CLAIM The ornamental design for a power bank, as shown and described. 